glTF exporter: fix normal export when normals are modified by modifier(s)

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (0, 9, 47),
+    "version": (0, 9, 48),
     'blender': (2, 80, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_extract.py

@@ -588,7 +588,7 @@ def extract_primitives(glTF, blender_mesh, blender_vertex_groups, modifiers, exp
             vertex = blender_mesh.vertices[vertex_index]
 
             v = convert_swizzle_location(vertex.co, export_settings)
-            if blender_polygon.use_smooth:
+            if blender_polygon.use_smooth or blender_mesh.use_auto_smooth:
                 if blender_mesh.has_custom_normals:
                     n = convert_swizzle_location(blender_mesh.loops[loop_index].normal, export_settings)
                 else:

io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py

@@ -224,6 +224,11 @@ def __gather_mesh(blender_object, export_settings):
     if blender_object.type != "MESH":
         return None
 
+    modifier_normal_types = [
+        "NORMAL_EDIT",
+        "WEIGHTED_NORMAL"
+    ]
+
     # If not using vertex group, they are irrelevant for caching --> ensure that they do not trigger a cache miss
     vertex_groups = blender_object.vertex_groups
     modifiers = blender_object.modifiers
@@ -239,7 +244,7 @@ def __gather_mesh(blender_object, export_settings):
             edge_split = blender_object.modifiers.new('Temporary_Auto_Smooth', 'EDGE_SPLIT')
             edge_split.split_angle = blender_object.data.auto_smooth_angle
             edge_split.use_edge_angle = not blender_object.data.has_custom_normals
-            blender_object.data.use_auto_smooth = False
+            blender_object.data.use_auto_smooth = any([m in modifier_normal_types for m in [mod.type for mod in blender_object.modifiers]])
             bpy.context.view_layer.update()
 
         armature_modifiers = {}